• State TI Thinks Resolved
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 30 subscribers
  • Views 154 views
  • Users 0 members are here
Support feedback
Options
Options
Related

DRV8873: Confirmation on using DRV8873 for 24V 8A Brushed DC Motor Control with Current Sensing

Dhruvit Bhimani
Intellectual 310 points
Part Number: DRV8873
Other Parts Discussed in Thread: DRV8702-Q1, DRV8706-Q1, DRV8705-Q1, DRV8703-Q1, DRV8701

Hi Team,

I’m evaluating the DRV8873 motor driver for my project and would like your confirmation on a few points before finalizing the design.

My application involves driving a 24 V, 8 A brushed DC motor with high torque. The motor position will be controlled through an external accelerometer, so precise speed and direction control are required.

Could you please confirm if the DRV8873 can meet the following requirements?

  1. It should be capable of supplying 8 A continuous current without thermal issues.

  2. It should operate reliably at 24 V nominal motor voltage.

  3. It should support motor current sensing for monitoring and control.

  4. Regarding the interface, the datasheet shows SPI, PWM, and GPIO logic options — can you clarify which interface is used for:

    • Reading current sense data

    • Fault detection and status feedback

Also, if the DRV8873 cannot fully meet these requirements, please suggest an alternative TI motor driver suitable for a 24 V, 8 A brushed DC motor with current sensing capability.

Best regards,
Dhruvit

  • 0
    TI__Mastermind 47595 points

    Hi Dhruvit,

    Thanks for your question.

    Dhruvit Bhimani said:
    It should be capable of supplying 8 A continuous current without thermal issues.

    This would depend on the power dissipation and the ambient temperature in the application. See section 8.2.1.2 Drive Current and Power Dissipation in the datasheet for power dissipation calculations. For 8 A, estimated conduction loss would be 8 x 8 x 0.15 = 9.6 W. The RθJA for this device 27.8 °C/W. Even without accounting for PTOT, just the conduction losses would increase the temperature of the device at TA = 25 °C to 9.6 x 27.8 + 25 = 291.9 °C, way higher than the 165 °C MIN of TSD. The driver cannot support this current. Based on this it could support perhaps one half of 8 A or 4 A tops at TA = 25 °C.

    Dhruvit Bhimani said:
    It should operate reliably at 24 V nominal motor voltage.

    Recommended operating max. voltage is 38 V. This includes potential transients during switching. As long this is in compliances there will be no concern for reliability.

    Dhruvit Bhimani said:
    It should support motor current sensing for monitoring and control.

    See datasheet. The DRV8873 has internal current sensing, IPROPI1,2 proportional current output and internal current regulation features.

    Dhruvit Bhimani said:

    Regarding the interface, the datasheet shows SPI, PWM, and GPIO logic options — can you clarify which interface is used for:

    • Reading current sense data

    • Fault detection and status feedback

    There are two orderable variants for this product. See below. The DRV8873H is fully GPIO based for configuration, control and fault diagnostics. The DRV8873S has SPI for configuration, control and fault diagnostics using registers as well as GPIO control options for inputs and fault reporting via nFAULT pin. 

    Current sense IPROPI1,2 analog output is similar in both H and S variants. More details in the datasheet. 

    Dhruvit Bhimani said:
    Also, if the DRV8873 cannot fully meet these requirements, please suggest an alternative TI motor driver suitable for a 24 V, 8 A brushed DC motor with current sensing capability.

    For 8 A continuous current rating which also mean the startup inrush current could be several times higher than that you may have to consider a gate driver IC with external MOSFETs. For example the DRV8701, DRV8702-Q1, DRV8703-Q1, DRV8705-Q1 or the DRV8706-Q1.

    Regards, Murugavel 

       

  • 0 in reply to Murugavel4637
    Intellectual 310 points

    Hi Murugavel,

    Attached are the details of the motor used in my application.

    Motor specifications:

    • Rated voltage: 24 V

    • Rated current: ≤ 8 A

    • Rated torque: 66 Nm

    • Speed: 12 rpm

    • Input power: 190 W

    The application is a solar tracking system, where the motor only moves in small ±1° steps and then stays in position for some time. This means the motor frequently starts from rest, so your earlier point about inrush (stall) current is quite important for my design.

    Could you please help me identify which driver among the following would be best suited for this use case?

    • DRV8701

    • DRV8702-Q1

    • DRV8703-Q1

    • DRV8705-Q1

    • DRV8706-Q1

    My main requirements are:

    1. 24 V operation with capability to handle startup surge current.

    2. Current sensing for control and protection.

    3. Fault diagnostics and easy MCU interface (SPI or analog sense).

    Thanks for your guidance so far — I’d appreciate your help in finalizing the right device.

    Best regards,
    Dhruvit

  • 0 in reply to Dhruvit Bhimani
    TI__Mastermind 47595 points

    Hi Dhruvit,

    Thanks for sharing the motor specification. This tells the rated current is < 8 A. It does not mention the continuous steady state current would be 8 A. Additional information such as inrush current, stall current is missing.

    You could measure the motor currents using a 24 V power supply source to drive the motor and an oscilloscope current probe to capture the inrush current with the mechanical load on the motor, the steady state current with mechanical load and the motor stall current. Based on this data we can suggest the right device for your application. Please share this information. 

    See this video to understand brushed DC motor driving, Driving a brushed DC motor | Video | TI.com. As well as this application brief, https://www.ti.com/lit/ab/slvafq3/slvafq3.pdf. Do you have a DRV8873 EVM with you? You could connect the motor directly to the EVM output and test it.  

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Intellectual 310 points

    Hi Murugavel,

    Sorry for the delayed reply — it’s vacation time here.

    Regarding the development kits, I don’t have any of them at present but I’m looking to select one based on your recommendation.

    I’ve reviewed the available motors and identified the maximum load that my controller will need to handle. Any other motor in my setup will have equal or lower ratings.

    Please find attached the datasheet of the motor I’m considering. I believe it includes all the parameters you mentioned to help select a suitable driver.

    As shown, the rated current is 6 A while the peak current reaches 15 A, which I understand corresponds to the inrush or stall current you referred to. Therefore, the driver must be capable of handling currents above 15 A. Based on this, I agree that a gate driver with external MOSFETs would be the right approach for this application.

    Best regards,
    Dhruvit

  • 0 in reply to Dhruvit Bhimani
    TI__Mastermind 47595 points

    Hi Dhruvit,

    Thanks for the additional information.

    Dhruvit Bhimani said:
    As shown, the rated current is 6 A while the peak current reaches 15 A, which I understand corresponds to the inrush or stall current you referred to. Therefore, the driver must be capable of handling currents above 15 A. Based on this, I agree that a gate driver with external MOSFETs would be the right approach for this application.

    Yes this is correct.

    Dhruvit Bhimani said:

    Could you please help me identify which driver among the following would be best suited for this use case?

    • DRV8701

    • DRV8702-Q1

    • DRV8703-Q1

    • DRV8705-Q1

    • DRV8706-Q1

    Any one of these devices are suitable for the application. The DRV8706S-Q1 would have the maximum features including diagnostics, however requires SPI communication and firmware configuration while the DRV8701 would be of minimalistic approach controlled by GPIO. The DRV8701, DRV8702-Q1 (GPIO control), DRV8703-Q1(GPIO and SPI control) have built-in current regulation feature. "-Q1" means industrial and automotive qualified and no "-Q1" suffix means industrial only. If your application is automotive you must use the "-Q1" products. Based on these you can choose one of these drivers. 

    You can refer to these application notes. https://www.ti.com/lit/ta/ssztcj4/ssztcj4.pdf and https://www.ti.com/lit/an/slva714d/slva714d.pdf. 

    Regards, Murugavel